The present invention relates to wind propelled craft adapted for movement over the surface of a medium, such as ice or water.
Sailing vessels have been utilized for water travel from the time of early recorded history, and a great many designs have been developed in order to accomplish the specific objective of the sailing craft, whether it be intended for commercial usage or for pleasure. A great many factors enter into the design of a sailing craft, such as the speed which it can attain in a given wind, its stability in high winds, the amount of sail which it is able to carry in high winds, its durability, and the like.
A common design of sailing craft comprises a single hull, which is generally elongated in shape and provided with a centerboard or keel. One or more masts connected to the hull carry the sails, and in the case of large, ocean going, commercial vessels extensively employed before the advent of steamships, an extremely complex system of masts, yardarms, stays, etc. were required to support and control the amount of sail which was necessary to propel the large hull and cargo load carried therein. A difficulty with a one-hull vessel is that the large contact area between the hull and water results in very substantial frictional drag thereby reducing the speed of the vessel. This drag is further increased by the necessity for having a massive keel in order to prevent overturning of the vessel in high winds.
In order to reduce the frictional drag between the hull and water, multiple hulled vessels, such as catamarans and trimarans, have been developed. In these vessels, the mast or masts and rigging are supported on a plurality of pontoons or floats, which are widely spaced from each other and which have a relatively small wetted surface when compared with a conventional single hulled vessel. Although multi-hulled vessels are capable of much higher speeds than conventional single hulled vessels, they are much more difficult to maneuver, especially when attempting to turn into the wind. Also, because the hulls are interconnected by means of a framework of elongated, tubular members, the vessel is generally not as durable as a single hulled vessel.
In order to overcome the problems and disadvantages of prior art sailing vessel designs, the vessel according to the present invention comprises a equilateral tetrahedral frame connected to three support members adapted to float on the surface of the water, and having a unique arrangement of sails.
One prior art sailing vessel employing a rigid frame which is generally tetrahedral in shape is disclosed in U.S. Pat. No. 3,395,664. In one embodiment, the frame comprises six interconnected tubular members defining a triangular base connected to three buoyant support members, and three triangular sides connected at an apex. In another embodiment, a lower tetrahedral frame made of similar members has a vertical mast connected to the apex thereof and is supported by a plurality of stays connected to the three corners of the triangular base. A problem with the first-discussed embodiment, is that the frame relies for support solely on the six interconnected tubular members, thereby making it unsuitable for operation in high winds or rough seas. In the second embodiment, the mast is merely connected to the tetrahedral frame and does not function as one of the structural members, thereby resulting in an unbalance of forces so as to substantially reduce the durability and overall strength of the vessel.
U.S. Pat. No. 3,991,694 discloses a semi-rigid wind propelled vessel wherein the mast is similarly connected to the apex of a tetrahedral frame and supported by a plurality of stays connected to the corners of the triangular base of the frame. Again, the stresses and forces are unequally distributed, and would not be suitable for oceangoing use, as is the case with the vessel according to the present invention.